1. Field of the Invention
The present invention relates to a coating adhesive strength and shear strength measuring apparatus and more particularly to a coating adhesive strength and shear strength measuring apparatus which can accurately measure the adhesive strength and the shear strength of a coating film bonded to a test piece while its structure is simple and low in the cost.
2. Description of the Related Art
Disclosed in Japanese Patent Laid-open Publication (Heisei)3-67151 is a conventional coating adhesive strength and shear strength measuring apparatus which comprises a cutting knife holder arranged for moving in two, vertical and parallel, directions relative to a vertical sliding guide shaft which can be moved in vertical to the coating surface of a test piece and a parallel sliding guide shaft which can be moved in parallel to the coating surface, a cutting knife mounted to the cutting guide shaft for slicing the coating, a vertical pressure sensor for measuring a repulsion in the vertical direction along the vertical sliding guide shaft, and a parallel pressure sensor for measuring a resistance to the cutting action in the parallel direction along the parallel sliding guide shaft.
The conventional coating adhesive strength and shear strength measuring apparatus is designed for measuring the repulsion in the vertical direction from a displacement of the vertical sliding guide shaft and the resistance to the cutting action in the parallel direction from a displacement of the parallel sliding guide shaft. Accordingly, a measurement of the repulsion includes a sliding related resistance derived from the displacement of the vertical sliding guide shaft while a measurement of the resistance to the cutting action includes a sliding related resistance derived from the displacement of the parallel sliding guide shaft.
It is however disadvantageous that the measurements of the repulsion and the resistance to the cutting action are substantially incorrect as they include the sliding related resistance on the sliding guide shafts.
Also, since there is a play gap (clearance) between the vertical sliding guide shaft and its supporting members, the depth of the cutting may be incorrect. Equally, as a play gap (clearance) is provided between the parallel sliding guide shaft and its supporting members, the cutting plane may hardly be smooth. Accordingly, the cutting plane will be elongated with much difficulty.
Moreover, the arrangement including both the vertical sliding guide shaft and the parallel sliding guide shaft becomes intricate and its overall cost win be increased.
It is hence an object of the present invention to provide a coating adhesive strength and shear strength measuring apparatus which can accurately measure the adhesive strength and the shear strength of the coating of a test piece while being simple in the structure and inexpensive in the cost.
As a first feature of the present invention, a coating adhesive strength and shear strength measuring apparatus for cutting the coating of a test piece with a cutting knife, measuring the force vertical to the coating and the force parallel to the coating which both are exerted on the cutting knife, and calculating the adhesive strength and the shear strength of the coating is provided comprising: a stage means arranged movable in two, vertical and parallel, directions relative to the coating; a vertical pressure sensor linked at one end to the stage means; a parallel pressure sensor linked at its first end to the other end of the vertical pressure sensor; and the cutting knife linked to the second end of the parallel pressure sensor, wherein the vertical force exerted on the cutting knife is measured by the vertical pressure sensor and the parallel force exerted on the cutting knife is measured by the parallel pressure sensor.
In action, the stage means may be moved while the test piece remains stationary. Alternatively, the test piece may be moved while the stage means remains stationary or both may be moved.
The coating adhesive strength and shear strength measuring apparatus of the first feature has the cutting knife mounted to the parallel pressure sensor with no sliding guide shaft disposed between the cutting knife and the parallel pressure sensor. This allows the parallel pressure to suffer from no sliding related resistance and its measurement to be accurate. Also, the cutting knife is linked by the parallel pressure sensor to the vertical pressure sensor with no sliding guide shaft disposed between the cutting knife and the vertical pressure sensor. This allows the vertical pressure to suffer from no sliding related resistance and its measurement to be accurate. Moreover, the cutting depth and the cutting plane can be affected by no sliding guide shaft play. Accordingly, both the adhesive strength and the shear strength of the coating of a test piece can be measured at higher accuracy. As no sliding guide shaft is involved, the structure of the apparatus will be simple and inexpensive.
As a second feature of the present invention, a coating adhesive strength and shear strength measuring apparatus for cutting the coating of a test piece with a cutting knife, measuring the force vertical to the coating and the force parallel to the coating which both are exerted on the cutting knife, and calculating the adhesive strength and the shear strength of the coating is provided comprising: a stage means arranged movable in two, vertical and parallel, directions relative to the coating; a parallel pressure sensor linked at one end to the stage means; a vertical pressure sensor linked at its first end to the other end of the parallel pressure sensor; and the cutting knife linked to the second end of the vertical pressure sensor, wherein the vertical force exerted on the cutting knife is measured by the vertical pressure sensor and the parallel force exerted on the cutting knife is measured by the parallel pressure sensor.
In action, the stage means may be moved while the test piece remains stationary. Alternatively, the test piece may be moved while the stage means remains stationary or both may be moved.
The coating adhesive strength and shear strength measuring apparatus of the second feature has the cutting knife mounted to the vertical pressure sensor with no sliding guide shaft disposed between the cutting knife and the vertical pressure sensor. This allows the vertical pressure to suffer from no sliding related resistance and thus its measurement to be accurate. Also, the cutting knife is linked by the vertical pressure sensor to the parallel pressure sensor with no sliding guide shaft disposed between the cutting knife and the parallel pressure sensor. This allows the parallel pressure to suffer from no sliding related resistance and thus its measurement to be accurate. Moreover, the cutting depth and the cutting plane can be affected by no sliding guide shaft play. Accordingly, both the adhesive strength and the shear strength of the coating of a test piece can be measured at higher accuracy. As no sliding guide shaft is involved, the structure of the apparatus will be simple and inexpensive.
As a third feature of the present invention, the coating adhesive strength and shear strength measuring apparatus is modified wherein the stage means is slightly moved up to 500 xcexcm by the action of piezoelectric devices.
The stage means may be implemented by an XY stage driven by a stepping motor or an ultrasonic oscillating motor. As the XY stage has sliding portions, its clearance should allow a margin of 1 xcexcm. The clearance may however produce an error in the measurement.
The coating adhesive strength and shear strength measuring apparatus of the third feature has the movable stage driven by piezoelectric devices and its overall components including the support base and the cutting knife can thus assembled integrally with no involvement of clearance. Accordingly, the measurement can be improved in the accuracy.
As a fourth feature of the present invention, the coating adhesive strength and shear strength measuring apparatus further comprises a graphic means for converting changes in the vertical pressure measured by the vertical pressure sensor, the parallel pressure measured by the parallel pressure sensor, and the depth of cutting by the cutting knife into graphic representations.
The coating adhesive strength and shear strength measuring apparatus of the fourth feature allows changes in the vertical pressure, the parallel pressure, and the cutting depth measured to be converted into graphic representations which can explicitly exhibit the relationship between the changes.